[dns-operations] DNS cookie bugs

[Tony Finch]

Mark Andrews <marka at isc.org> wrote:
>
> I really don’t understand how a DNS developer could decide that it was
> sensible to echo back data that the server does not understand.  Most of
> the servers that do this appeared on the net *after* RCF 6891 was
> published.  See: http://ednscomp.isc.org/compliance/ts/gov.optfail.html

This one is a different kind of weirdness. The garbage in the server
cookie varies a bit depending on the type but otherwise seems to be almost
always the same.

; <<>> DiG 9.12.0rc1 <<>> +qr +multi +norec www.europarl.europa.eu aaaa @136.173.159.209
;; global options: +cmd
;; Sending:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 8516
;; flags: ad; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: 73f12a825df4386c
;; QUESTION SECTION:
;www.europarl.europa.eu.        IN AAAA

;; QUERY SIZE: 63

;; Warning: Client COOKIE mismatch
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 8516
;; flags: qr aa; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: 000000000000000030cebe4a2a00000030cebe4a2a000000 (bad)
;; QUESTION SECTION:
;www.europarl.europa.eu.        IN AAAA

;; AUTHORITY SECTION:
europarl.europa.eu.     3600 IN SOA presluxsdnsout.europarl.europa.eu. dnsadmin.europarl.europa.eu. (
                                2017120500 ; serial
                                3600       ; refresh (1 hour)
                                3600       ; retry (1 hour)
                                86400      ; expire (1 day)
                                3600       ; minimum (1 hour)
                                )

;; Query time: 19 msec
;; SERVER: 136.173.159.209#53(136.173.159.209)
;; WHEN: Fri Dec 08 12:10:44 GMT 2017
;; MSG SIZE  rcvd: 139

Tony.
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